This article is not part of the John Wick universe. This article covers a subject that is part of the real world, and thus should not be taken as a part of the John Wick universe.
William James "Willem" Dafoe is the actor who plays Marcus.
Dafoe was born in Appleton, Wisconsin. His most notable acting works outside of John Wick are Spiderman, Justice League, Aquaman, Finding Nemo, Finding Dory and more.